KrF photoresist film-forming resin as well as preparation method and application thereof

Abstract

The invention relates to the technical field of photoresist film-forming resin preparation, and discloses KrF photoresist film-forming resin and a preparation method and application thereof.The preparation method comprises the steps that 4-acetoxystyrene monomers or 4-acetoxystyrene monomers and other comonomers are filtered and then added into a dispersing agent, stirring is conducted, and the KrF photoresist film-forming resin is obtained; adding an organic photocatalyst and a chain transfer agent, and mixing to obtain a mixed solution; introducing inert gas into the mixed solution, irradiating the mixed solution under the condition of visible light, and reacting to obtain a polymer solution; and separating out the polymerization liquid, drying, adding ammonia water or a hydrazine hydrate solution, and reacting to obtain the KrF photoresist film-forming resin of which the molecular weight distribution is less than 1.2. By adopting a photo-initiation mode, on one hand, the energy consumption in the polymerization process can be reduced, and the reaction conditions are mild; on the other hand, the preparation process of the polymer can be well controlled in time and space, and the inter-batch stability is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of photoresist film-forming resin preparation, and particularly relates to a KrF photoresist film-forming resin and a preparation method and application thereof. Background Art

[0002] Photoresist, also known as photoresist, is a polymer material that is highly sensitive to light and radiation. Under the irradiation or radiation of ultraviolet rays, electron beams, excimer laser beams, ion beams, X-rays, etc., the material can undergo photochemical changes, resulting in changes in the solubility characteristics of its film before and after exposure. The composition of photoresist usually includes film-forming resin, photosensitizer, inhibitor, solvent and some additives. Among them, the film-forming resin is the core part of the photoresist, and different resin properties will have different influences and effects on the performance of the photoresist. KrF photoresist is a deep ultraviolet (DUV) photoresist with an exposure wavelength of 248nm. This photoresist has important applications in semiconductor process technology, especially in 3D NAND stacking architecture. Due to the increase in the number of stacking layers, the demand for KrF photoresist will increase significantly. The film-forming resin of KrF photoresist is mainly poly(p-hydroxystyrene), PHS, among which the preparation stability and molecular weight distribution of the resin and the residual metal ions are the main factors affecting its performance. The wide molecular weight distribution will lead to differences in the solution rate in different areas during the photolithography process, resulting in reduced resolution. At the same time, the preparation stability of the resin directly affects the molecular weight of different batches of resin, and ultimately affects the stability of the photolithography process. The molecular weight distribution (Polymer dispersity index, PDI) of PHS resin polymers prepared by traditional free radical polymerization technology is basically greater than 1.4, and the molecular weight is uncontrollable, which cannot meet the requirements of high-performance photoresist.

[0003] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a KrF photoresist film-forming resin and a preparation method and application thereof, aiming to solve the problem that the molecular weight distribution of the PHS resin polymer prepared by the prior art is basically greater than 1.4, and the molecular weight is uncontrollable, and cannot meet the requirements of high-performance photoresist.

[0005] The technical solution of the present invention is as follows:

[0006] A method for preparing a KrF photoresist film-forming resin, comprising the steps of:

[0007] Filtering 4-acetoxystyrene monomer or 4-acetoxystyrene monomer and other copolymerized monomers through neutral alumina particles, then adding them to a dispersant, and adding an organic photocatalyst and a chain transfer agent to mix, to obtain a mixed solution;

[0008] Inert gas is introduced into the mixed solution to remove oxygen from the mixed solution at 4-40 mW / cm 2 The mixed solution is irradiated under visible light conditions, and reacted at 25-60° C. for 10-72 hours to obtain a polymer solution;

[0009] The polymer solution is dropped into a poor solvent for precipitation, dried, and then dispersed in an organic solvent, and ammonia water or hydrazine hydrate solution is added and stirred for 3-24 hours. After the reaction is completed, the obtained polymer precipitate is washed and dried to obtain a KrF photoresist film-forming resin with a molecular weight distribution of <1.2 and a molecular weight of 3000-100000.

[0010] The method for preparing the KrF photoresist film-forming resin, wherein the other comonomers are one or more of styrene, 2-acetoxystyrene, tert-butoxycarbonylstyrene, tert-butyl acrylate, tert-butyl methacrylate and tert-butoxystyrene.

[0011] The method for preparing the KrF photoresist film-forming resin, wherein the molar ratio of the other comonomers to the 4-acetoxystyrene monomer is 0.1-1:1.

[0012] The preparation method of the KrF photoresist film-forming resin, wherein the organic photocatalyst is one or more of eosin, fluorescein, phenothiazine, phenazine, cyanoarene, 1,3-propanedithiol, 1,2-ethanedithiol, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrathioacetate and pentaerythritol tetra-3-mercaptopropionate.

[0013] The preparation method of the KrF photoresist film-forming resin, wherein the chain transfer agent is one or more of 4-cyano-4-[(dodecylthiocarbonyl)-thio]pentanoic acid, 2-(dodecyltrithiocarbonate)-2-methylpropionic acid, 4-cyano-4-(thiobenzoyl)pentanoic acid, O-phenyl S-(1-phenylethyl) dithiocarbonate, O-ethyl S-(1-phenylethyl) dithiocarbonate and methyl (phenyl) aminodithiocarboxylic acid cyanomethyl ester, and the molar ratio of the chain transfer agent to the polymerization monomer is 1:20-600.

[0014] The preparation method of the KrF photoresist film-forming resin, wherein the dispersant is one or more of tetrahydrofuran, toluene, xylene, ethylene diether, cyclohexane, N,N-dimethylformamide, N,N-dimethylacetamide, ethane, heptane, n-heptane, ethyl acetate, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol methyl ether acetate and dimethyl sulfoxide.

[0015] The method for preparing the KrF photoresist film-forming resin, wherein the poor solvent is one or more of ether, petroleum ether, n-hexane, n-pentane, n-heptane, methanol, ethanol, water and isopropanol; and the organic solvent is methanol, tetrahydrofuran or 1,4-dioxane.

[0016] A KrF photoresist film-forming resin is prepared by adopting the preparation method of the KrF photoresist film-forming resin of the present invention.

[0017] An application of a KrF photoresist film-forming resin, wherein the KrF photoresist film-forming resin of the invention is used to prepare KrF photoresist.

[0018] Beneficial effects: The present invention adopts light-controlled RAFT polymerization technology, which can better prepare narrow distribution KrF photoresist film-forming resin with molecular weight distribution <1.2 compared with traditional free radical polymerization technology; and because of the light-initiated method, on the one hand, it can reduce the energy consumption in the polymerization process and the reaction conditions are mild; on the other hand, it can control the polymer preparation process in time and space, realize accurate control of polymer molecular weight, and ensure the batch stability of the product. In addition, compared with anionic polymerization and ATRP, this method does not use metal ion catalysts, reduces the process complexity of metal ion removal in the post-treatment process, and ensures low metal ion residues in the sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is a flow chart of a method for preparing a KrF photoresist film-forming resin.

[0020] Figure 2 This is a graph showing the results of number average molecular weight and PDI testing of the KrF photoresist film-forming resin prepared in Example 2.

[0021] Figure 3 This is a comparison chart of the results of number average molecular weight and molecular weight distribution (Polymer dispersity index, PDI) testing of three batches of KrF photoresist film-forming resins prepared by the method of Example 1. DETAILED DESCRIPTION

[0022] The present invention provides a KrF photoresist film-forming resin and a preparation method and application thereof. To make the purpose, technical scheme and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0023] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "including" or "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0024] For ease of understanding, the specific process of the embodiment of the present invention is described below. Figure 1 The first embodiment of a method for preparing a KrF photoresist film-forming resin in an embodiment of the present invention comprises:

[0025] S10, filtering 4-acetoxystyrene monomer or 4-acetoxystyrene monomer and other comonomers through neutral alumina particles to remove the polymerization inhibitor, then adding them to a dispersant, and adding an organic photocatalyst and a chain transfer agent to mix to obtain a mixed solution;

[0026] Specifically, the 4-acetoxystyrene monomer described in this embodiment as the main building block of the polymer chain can be connected by covalent bonds alone to form a long-chain polymer, and can also be copolymerized with other comonomers to form a long-chain polymer. The monomer structure of the 4-acetoxystyrene is as follows: The neutral alumina particles are used as filtering media, and their main function is to remove the inhibitor in the monomer solution to ensure the smooth progress of the polymerization reaction; the dispersant is mainly used to help the monomer and other additives to be better dispersed in the solution to prevent agglomeration and precipitation; the main function of the organic photocatalyst is to be excited under light, transition from the ground state to the excited state, and then react with the chain transfer agent to control the RAFT (reversible addition-fragmentation chain transfer) balance; the role of the chain transfer agent is to protect the free radicals by chain transfer, so that most of the free radicals in the polymerization reaction system are in a dormant state, and through a dynamic reversible reaction, the activation and dormant states are switched to each other, so that the growth probability of each polymer chain segment is equal, thereby achieving the control of the polymer molecular weight and molecular weight distribution. The steps of this embodiment mainly involve the mixing of monomers and the addition of catalysts and chain transfer agents to prepare for the subsequent polymerization reaction.

[0027] S20, introduce inert gas into the mixed solution to remove oxygen in the mixed solution, at 4-40mW / cm 2 The mixed solution is irradiated under visible light conditions, and reacted at 25-60° C. for 10-72 hours to obtain a polymer solution;

[0028] In this embodiment, oxygen in the mixed solution is removed by introducing an inert gas to prevent oxygen from interfering with the polymerization reaction as a free radical scavenger, and the light energy required for the polymerization reaction is provided by visible light irradiation to activate the organic photocatalyst to generate free radicals to start the polymerization reaction. The reaction temperature is controlled to 25-60°C to promote collision and reaction between monomers at a suitable temperature. In this step, the organic photocatalyst is activated under visible light irradiation to initiate the polymerization reaction between the monomers. By selecting different chain transfer agents, the molecular weight and molecular weight distribution of the polymer can be accurately controlled to ensure that the performance of the resin meets the requirements. In this embodiment, the wavelength selection of the visible light is related to the selection of the photoinitiator and the chain transfer agent, and the preferred wavelength is 340-540nm.

[0029] S30, dropping the polymer solution into a poor solvent for precipitation, drying, and then dispersing it in an organic solvent, adding ammonia water or hydrazine hydrate solution and continuing stirring for 3-24 hours. After the reaction is completed, the obtained polymer precipitate is washed and dried to obtain a KrF photoresist film-forming resin with a molecular weight distribution of <1.2 and a molecular weight of 3000-100000.

[0030] In this embodiment, the polymer solution is dripped into a poor solvent to precipitate the polymer from the solution, the polymer is separated from the solvent, and the residual solvent in the polymer is removed by drying; then the polymer is redispersed with the help of an organic solvent to facilitate subsequent reactions; then ammonia water or a hydrazine hydrate solution is added, and the acetoxy group in the polymer is hydrolyzed under alkaline conditions to generate hydroxyl groups and acetate ions, and finally, the polymer is precipitated again, washed, and dried to obtain a purified KrF photoresist film-forming resin with a molecular weight distribution of <1.2. In this embodiment, the acetoxy group is hydrolyzed into a hydroxyl group, and a hydroxyl functional group can be introduced to provide additional reactivity and functionality to the photoresist film-forming resin.

[0031] This embodiment uses an organic photocatalyst and visible light irradiation to carry out a polymerization reaction, which has the advantages of mild reaction conditions and easy control. The use of a chain transfer agent can effectively control the molecular weight and molecular weight distribution of the polymer to ensure stable performance of the resin.

[0032] The PDI (molecular weight distribution) of the photoresist film-forming resin prepared in this embodiment is less than 1.2, which means that the molecular weight distribution of the resin is very narrow, that is, the lengths of the molecular chains in the resin are very small. This photoresist film-forming resin with a narrow molecular weight distribution has many significant advantages: first, the resin with a narrow molecular weight distribution can form a more uniform and smooth film during film formation, because molecular chains with similar molecular weights are more likely to be arranged in an orderly manner during the film formation process, reducing the generation of defects and pores; and the uniform and dense film can more accurately transmit the photolithography pattern and improve the resolution and accuracy of the photolithography, which is crucial for manufacturing patterns of microstructures, such as micrometer-level patterns in chip manufacturing; the resin with a narrow molecular weight distribution usually has better chemical stability and can resist various chemical corrosion and reactions during the photolithography process, thereby extending the service life and stability of the photoresist.

[0033] In some embodiments, the other comonomers are one or more of styrene, 2-acetoxystyrene, tert-butyloxycarbonylstyrene, tert-butyl acrylate, tert-butyl methacrylate and tert-butyloxystyrene. In this embodiment, the styrene, as a basic chemical raw material, has a low deep ultraviolet light absorptivity. As a comonomer for preparing KrF photoresist film-forming resin, it helps to improve certain specific properties of the resin, such as hardness and wear resistance; the tert-butyloxycarbonylstyrene has high purity and low metal ion content, which can reduce the generation of by-products during the polymerization process and improve the yield of the target product. At the same time, its special structure helps to improve the resolution of the photoresist and the quality of the photolithographic pattern; the tert-butyl acrylate has good hydrophobicity and hydrolysis stability. The introduction of tert-butyl acrylate in the photoresist resin can improve the water resistance and durability of the resin. At the same time, its good color development and weather resistance also help to improve the overall performance of the photoresist. In addition, the addition of tert-butyl acrylate can also increase the cohesive energy density of the resin, thereby improving the durability of the polymer film and the protection of the substrate. In this embodiment, different types of comonomers can be selected according to specific needs to copolymerize with the 4-acetoxystyrene monomer to generate the KrF photoresist film-forming resin.

[0034] In some embodiments, the molar ratio of the other comonomers to the 4-acetoxystyrene monomer is 0.1-1: 1. Specifically, the photoresist film-forming resin is a key material in photolithography technology, which requires good light transparency, dry corrosion resistance, high resolution and suitable processing performance. The appropriate molar ratio between the other comonomers and the 4-acetoxystyrene monomer should ensure that there is a sufficient number of p-hydroxystyrene units in the copolymer, which can provide good light transparency during the photolithography process, so that the photoresist can accurately transmit light signals. Taking tert-butyl acrylate as a comonomer as an example, the molar ratio of the tert-butyl acrylate to the 4-acetoxystyrene monomer is 0.3-1:1. Since the tert-butyl acrylate can only provide the p-hydroxystyrene unit from the 4-acetoxystyrene monomer during the copolymerization process with the tert-butyl acrylate and the 4-acetoxystyrene monomer, if the molar ratio of the tert-butyl acrylate to the 4-acetoxystyrene monomer is too high, it may lead to insufficient number of p-hydroxystyrene units in the final copolymer, affecting the light transparency; if the molar ratio is too low, it may cause the copolymer to be too complex, also affecting the photolithography effect; within this molar ratio range, the copolymer molecular chain can be made to form a clear pattern more easily during the photolithography process, thereby improving the resolution, and the copolymer can also have good processing properties, such as appropriate melting point and fluidity, which is convenient for the coating and processing of the photoresist. This embodiment can achieve fine control of the performance of the KrF photoresist film-forming resin by accurately controlling the molar ratio of the comonomer to the 4-acetoxystyrene monomer, meeting the needs of different photolithography processes.

[0035] In some embodiments, the organic photocatalyst is one or more of eosin, fluorescein, phenothiazine, phenazine, cyanoarene, 1,3-propanedithiol, 1,2-ethanedithiol, trimethylolpropane tris (3-mercaptopropionate), pentaerythritol tetramercaptoacetate and pentaerythritol tetra-3-mercaptopropionate. When one or more of the above organic photocatalysts are selected to catalyze the preparation of KrF photoresist film-forming resin, a suitable catalyst can be selected according to specific needs and reaction conditions. These catalysts each have their own characteristics and advantages, and can jointly promote the progress of the polymerization reaction, improve the reaction efficiency and the performance of the resin. As an example, this embodiment preferably uses eosin and 1,3-propanedithiol as organic photocatalysts, wherein eosin has high photosensitivity, can respond quickly to light and initiate polymerization; and another catalyst 1,3-propanedithiol has strong chemical stability, can stably exist and play a catalytic role during the reaction; when these two catalysts are used together, they can cooperate with each other to jointly promote the progress of the polymerization reaction, thereby improving the reaction efficiency and the performance of the resin.

[0036] In some embodiments, the chain transfer agent is one or more of 4-cyano-4-[(dodecylthiocarbonyl)-thio]pentanoic acid, 2-(dodecyltrithiocarbonate)-2-methylpropionic acid, 4-cyano-4-(thiobenzoyl)pentanoic acid, O-phenyl S-(1-phenylethyl) dithiocarbonate, O-ethyl S-(1-phenylethyl) dithiocarbonate and methyl(phenyl)aminodithiocarboxylic acid cyanomethyl ester. In the present embodiment, the 4-cyano-4-[(dodecylthiocarbonyl)-thio]pentanoic acid contains cyano and thiocarbonyl functional groups, has strong reactivity and chemical stability, can effectively control the length and distribution of the molecular chain in the polymerization reaction, improve the molecular weight of the resin and the control accuracy of the molecular weight distribution, thereby optimizing the performance of the resin; the 2-(dodecyl trithiocarbonate)-2-methylpropionic acid contains trithiocarbonate and methylpropionic acid groups, has unique chain transfer ability and good thermal stability, can efficiently transfer chain free radicals in the polymerization process, while maintaining the thermal stability of the resin. These chain transfer agents each have their own characteristics and advantages in the catalytic preparation of KrF photoresist film-forming resins. By reasonably selecting and using these chain transfer agents, the molecular structure and performance of the resin can be accurately controlled, thereby meeting the specific requirements of different fields for photoresist film-forming resins. Preferably, the molar ratio of the chain transfer agent to the polymerized monomer is 1:20-600, but is not limited thereto.

[0037] In some specific embodiments, 4-acetoxystyrene monomer and tert-butyl acrylate are filtered through neutral alumina particles, then added to a dispersant, and an organic photocatalyst and a chain transfer agent are added and mixed to obtain a mixed solution, wherein the organic photocatalyst consists of eosin and 1,3-propanedithiol; the chain transfer agent consists of 4-cyano-4-[(dodecylthiocarbonyl)-thio]pentanoic acid and 2-(dodecyltrithiocarbonate)-2-methylpropionic acid.

[0038] In the present embodiment, tert-butyl acrylate is selected as a comonomer to copolymerize with 4-acetoxystyrene monomer to prepare KrF photoresist film-forming resin, and the tert-butyl acrylate has good hydrophobicity and hydrolytic stability, and the introduction of tert-butyl acrylate in the photoresist resin can improve the water resistance and durability of the resin, and at the same time, its good color development and weather resistance also contribute to the overall performance of the photoresist. In addition, the addition of tert-butyl acrylate can also increase the cohesive energy density of the resin, thereby improving the durability of the polymer film and the protection of the substrate. The preferred tert-butyl acrylate of the present embodiment is 0.1-1:1 in the molar ratio with 4-acetoxystyrene monomer, and within the molar ratio range, it can be ensured that there are a sufficient number of p-hydroxystyrene units in the copolymer, so that the photoresist can accurately transmit light signals, and within the molar ratio range, the copolymer molecular chain can be made to be easier to form a clear pattern in the photolithography process, thereby improving the resolution, and the copolymer can also be made to have good processing properties, such as appropriate melting point and fluidity, which is convenient for the coating and processing of the photoresist. The present embodiment preferably uses eosin and 1,3-propanedithiol as organic photocatalysts, wherein eosin has high photosensitivity, can respond quickly to light and initiate polymerization, and another catalyst 1,3-propanedithiol has strong chemical stability, can stably exist and play a catalytic role in the reaction process; when these two catalysts are used together, they can cooperate with each other to promote the polymerization reaction, thereby improving the reaction efficiency and the performance of the resin. The present embodiment selects 4-cyano-4-[(dodecylthiocarbonyl)-thio]pentanoic acid and 2-(dodecyl trithiocarbonate)-2-methylpropionic acid as chain transfer agents, which can ensure efficient transfer of chain radicals during the polymerization process, reduce the degree of polymerization, and effectively control the length and distribution of the molecular chain, and can also optimize the performance of the resin, maintain the thermal stability of the resin, and help improve the resolution and heat resistance of the photoresist.

[0039] In some embodiments, the dispersant is one or more of tetrahydrofuran, toluene, xylene, ethylene diether, cyclohexane, N,N-dimethylformamide, N,N-dimethylacetamide, ethane, heptane, n-heptane, ethyl acetate, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol methyl ether acetate and dimethyl sulfoxide, but is not limited thereto.

[0040] In some embodiments, the poor solvent is one of ether, petroleum ether, n-hexane, n-pentane, n-heptane, methanol, ethanol, water and isopropanol, but not limited thereto; the organic solvent is methanol or 1,4-dioxane, but not limited thereto.

[0041] In some embodiments, a KrF photoresist film-forming resin is also provided, which is prepared by the preparation method of the KrF photoresist film-forming resin of the present invention.

[0042] In some embodiments, an application of a KrF photoresist film-forming resin is also provided, wherein the KrF photoresist film-forming resin of the present invention is used to prepare a KrF photoresist. In this embodiment, the KrF photoresist is a photosensitive mixed liquid, which is mainly used in the photolithography process in semiconductor manufacturing. It can transfer the image on the mask to the silicon chip, and play the role of sensing light and depicting patterns. In the photolithography process, the KrF photoresist is very sensitive to 248 nanometer ultraviolet light, so it can accurately copy the pattern on the photoresist. The KrF photoresist film-forming resin prepared by the present invention has excellent optical properties and chemical stability, and can be widely used in 248nm photoresist systems. And the present invention prepares a narrow distribution of KrF photoresist film-forming resin with a molecular weight distribution of <1.2, which means that the molecular weight distribution of the resin is very narrow, that is, the length of each molecular chain in the resin is very small. This narrow molecular weight distribution of photoresist film-forming resin has many significant benefits: first, the resin with a narrow molecular weight distribution can form a more uniform and smooth film when forming a film. This is because molecular chains with similar molecular weights are more likely to align with each other during the film-forming process, reducing the generation of defects and pores; and the uniform and dense film can more accurately transfer the photolithography pattern and improve the resolution and accuracy of the photolithography, which is crucial for manufacturing patterns of tiny structures, such as micron-level patterns in chip manufacturing; resins with a narrow molecular weight distribution usually have better chemical stability and can resist various chemical corrosion and reactions during the photolithography process, thereby extending the service life and stability of the photoresist.

[0043] The present invention will be further explained below by means of specific embodiments:

[0044] Example 1

[0045] A method for preparing a KrF photoresist film-forming resin comprises the following steps:

[0046] 16.22 g of 4-acetoxystyrene monomer was filtered through neutral alumina particles, then added to 48.52 mL of cyclohexane, 0.058 g of eosin was added as a catalyst, and 0.36 g of 4-cyano-4-[(dodecylthiocarbonyl)-thio]pentanoic acid was added as a chain transfer agent to obtain a mixed solution;

[0047] The mixed solution was evacuated and nitrogen was introduced into the mixed solution to remove oxygen from the mixed solution. 2 The mixed solution is irradiated under visible light conditions, and reacted at 40° C. for 24 hours to obtain a polymer solution;

[0048] The polymer solution is dropped into methanol to precipitate, dried, and then dispersed in methanol. A hydrazine hydrate solution is added and stirred for 10 hours. After the reaction is completed, the precipitate is washed and dried again to obtain a KrF photoresist film-forming resin.

[0049] Example 2

[0050] A method for preparing a KrF photoresist film-forming resin comprises the following steps:

[0051] 8.11 g of 4-acetoxystyrene monomer and 5.21 g of styrene monomer were weighed, filtered through neutral alumina particles, added to 27.78 mL of tetrahydrofuran, and then 0.012 g of fluorescein was added as a catalyst, and 0.26 g of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid was added as a chain transfer agent to obtain a mixed solution;

[0052] The mixed solution was evacuated and nitrogen was introduced into the mixed solution to remove oxygen from the mixed solution. 2 The mixed solution is irradiated under visible light conditions, and reacted at 25° C. for 12 hours to obtain a polymer solution;

[0053] The polymer solution is dropped into a poor solvent to precipitate, dried, and then dispersed in an organic solvent. Ammonia water is added and stirring is continued for 10 hours. After the reaction is completed, the precipitate is washed and dried again to obtain a KrF photoresist film-forming resin.

[0054] Example 3

[0055] A method for preparing a KrF photoresist film-forming resin comprises the following steps:

[0056] 16.22 g of 4-acetoxystyrene monomer and 7.69 g of tert-butyl acrylate monomer were filtered through neutral alumina particles, then added to 105 mL of tetrahydrofuran, 0.029 g of eosin and 0.004 g of 1,3-propanedithiol were added as catalysts, 0.18 g of 4-cyano-4-[(dodecylthiocarbonyl)-thio]pentanoic acid and 0.08 g of 2-(dodecyltrithiocarbonate)-2-methylpropionic acid were added as chain transfer agents to obtain a mixed solution;

[0057] The mixed solution was evacuated and argon was introduced into the mixed solution to remove oxygen from the mixed solution. 2The mixed solution is irradiated with blue light (460 nm) and reacted at 25° C. for 48 hours to obtain a polymer solution;

[0058] The polymer solution is dropped into n-hexane to precipitate, dried, and then dispersed in 1,4-dioxane. Hydrazine hydrate is added and stirred for 12 hours. After the reaction is completed, the precipitate is washed again with acetic acid solution and dried to obtain a KrF photoresist film-forming resin.

[0059] Test Case

[0060] The KrF photoresist film-forming resins prepared in Examples 1 to 3 were subjected to number average molecular weight measurement and PDI test. The results are shown in Tables 1 and Figure 2-Figure 3 shown.

[0061] Table 1 Number average molecular weight and PDI test results of KrF photoresist film-forming resin

[0062] serial number Number average molecular weight PDI Example 1 13480 1.10 Example 2 15334 1.12 Example 3 14050 1.04

[0063] It can be seen from the data in Table 1 that the PDI of the KrF photoresist film-forming resins prepared in Examples 1-3 is less than 1.2, which means that the molecular weight distribution of the resin prepared by the method of the present invention is very narrow, that is, the lengths of the molecular chains in the resin are very different. The photoresist film-forming resin with a narrow molecular weight distribution has many significant advantages: first, the resin with a narrow molecular weight distribution can form a more uniform and smooth film during film formation, because molecular chains with similar molecular weights are more likely to be arranged neatly with each other during the film formation process, reducing the generation of defects and pores; and the uniform and dense film can more accurately transmit the photolithography pattern and improve the resolution and accuracy of the photolithography, which is crucial for manufacturing patterns of tiny structures, such as micron-level patterns in chip manufacturing; the resin with a narrow molecular weight distribution usually has better chemical stability and can resist various chemical corrosion and reactions during the photolithography process, thereby extending the service life and stability of the photoresist.

[0064] It can also be seen from the above data that in this Example 3, tert-butyl acrylate is used as a comonomer, eosin and 1,3-propanedithiol are used as catalysts, 4-cyano-4-[(dodecylthiocarbonyl)-thio]pentanoic acid and 2-(dodecyltrithiocarbonate)-2-methylpropionic acid are used as chain transfer agents, and the PDI of the KrF photoresist film-forming resin finally prepared is the smallest, which is only 1.04, indicating that the length difference of each molecular chain in the resin in this example is the smallest, and it can form a more uniform and smooth film during film formation, and has better performance as a photoresist film-forming resin.

[0065] Figure 2 This is a graph showing the results of number average molecular weight and PDI testing of the KrF photoresist film-forming resin prepared in Example 2. Figure 3 The figure is a comparison of the results of number average molecular weight and PDI testing of three batches of KrF photoresist film-forming resins prepared by the method of Example 1. It can be seen from the figure that the molecular weight data of the three batches of KrF photoresist film-forming resins prepared are slightly different, and the PDI values ​​are all around 1.1, which shows that the present invention can ensure the batch-to-batch stability of the prepared KrF photoresist film-forming resin by controlling the polymer preparation process in time and space very well.

[0066] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a KrF photoresist film-forming resin, characterized in that: Includes steps: Filtering 4-acetoxystyrene monomer or 4-acetoxystyrene monomer and other copolymerized monomers through neutral alumina particles, then adding them to a dispersant, and adding an organic photocatalyst and a chain transfer agent to mix, to obtain a mixed solution; The mixed solution was evacuated and an inert gas was introduced into the mixed solution to remove oxygen from the mixed solution. 2 The mixed solution is irradiated under visible light conditions, and reacted at 25-60° C. for 10-72 hours to obtain a polymer solution; The polymer solution is dropped into a poor solvent for precipitation, dried, and then dispersed in an organic solvent, and ammonia water or hydrazine hydrate solution is added and stirred for 3-24 hours. After the reaction is completed, the obtained polymer precipitate is washed and dried to obtain a KrF photoresist film-forming resin with a molecular weight distribution of <1.2 and a molecular weight of 3000-100000.

2. The method for preparing the KrF photoresist film-forming resin according to claim 1, characterized in that: The other comonomers are one or more of styrene, 2-acetoxystyrene, tert-butoxycarbonylstyrene, tert-butyl acrylate, tert-butyl methacrylate, and tert-butoxystyrene.

3. The method for preparing the KrF photoresist film-forming resin according to claim 2, characterized in that: The molar ratio of the other comonomers to the 4-acetoxystyrene monomer is 0.1-1:

1.

4. The method for preparing the KrF photoresist film-forming resin according to claim 1, characterized in that: The organic photocatalyst is one or more of eosin, fluorescein, phenothiazine, phenazine, cyanoarene, 1,3-propanedithiol, 1,2-ethanedithiol, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrathioacetate and pentaerythritol tetra-3-mercaptopropionate.

5. The method for preparing the KrF photoresist film-forming resin according to claim 1, characterized in that: The chain transfer agent is one or more of 4-cyano-4-[(dodecylthiocarbonyl)-thio]pentanoic acid, 2-(dodecyltrithiocarbonate)-2-methylpropionic acid, 4-cyano-4-(thiobenzoyl)pentanoic acid, O-phenyl S-(1-phenylethyl) dithiocarbonate, O-ethyl S-(1-phenylethyl) dithiocarbonate and methyl (phenyl) amino dithiocarboxylic acid cyanomethyl ester. The molar ratio of the chain transfer agent to the monomer is 1:20-600.

6. The method for preparing the KrF photoresist film-forming resin according to claim 1, characterized in that: The dispersant is one or more of tetrahydrofuran, toluene, xylene, ethylene diether, cyclohexane, N,N-dimethylformamide, N,N-dimethylacetamide, ethane, heptane, n-heptane, ethyl acetate, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol methyl ether acetate and dimethyl sulfoxide.

7. The method for preparing the KrF photoresist film-forming resin according to claim 1, characterized in that: The poor solvent is one or more of ether, petroleum ether, n-hexane, n-pentane, n-heptane, methanol, ethanol, water and isopropanol; the organic solvent is methanol, tetrahydrofuran or 1,4-dioxane.

8. A KrF photoresist film-forming resin, characterized in that: The KrF photoresist film-forming resin is prepared by the preparation method of any one of claims 1 to 7.

9. An application of a KrF photoresist film-forming resin, characterized in that: The KrF photoresist film-forming resin according to claim 8 is used to prepare KrF photoresist.

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